Pixel
A pixel is a small snippet of code on a page (or an SDK inside an app) that sends events — a pageview, a click, a conversion — back to the ad platform. The platform uses that data to learn who actually converts and to build lookalike audiences from it.
How a pixel works with a PWA funnel
In a PWA funnel, the pixel usually sits on the prelander or the PWA page itself and fires on key actions — open, install, an in-app target event. The catch is that a browser pixel is client-side code, and it can be blocked by Safari's ITP, an ad blocker, or the user's own privacy settings, which means part of your real conversions never reach the platform.
Pixel plus server-side event delivery
To avoid losing data to browser-side blocking, the pixel is usually paired with server-side event delivery straight from the tracker. APEX handles this through postbacks and S2S integration, such as Keitaro-to-FB-CAPI, so a conversion still reaches the platform even if the browser pixel fails to fire for any reason.
FAQ
- Why might one pixel not be enough?
- Because the browser can block it from firing — due to ITP, an ad blocker, or user privacy settings — and part of your real conversions never make it into the platform's stats. That directly hurts ad optimization.
- How does a pixel relate to CAPI?
- A pixel sends events from the browser, while CAPI sends them from the server, and together they cover the same event from two angles, cutting data loss. The platform merges and deduplicates signals from both sources.
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